Refrigeration system having dual compressors and either a single evaporator or dual evaporators

ABSTRACT

A refrigeration system having either a single evaporator or dual evaporators where a flash chamber is used with first and second compressor stages. The flash chamber separates the refrigerant mixture from a high-stage capillary into liquid and gas, where the liquid is directed to a low-stage capillary and the gas is directed back to the first compressor. Additionally, the flash chamber may also be used for intercooling the gas going from the second compressor to the first compressor. For dual evaporator systems, this system is especially good for compartments where a first compartment requires a very low evaporator temperature and a second compartment requires a controllable evaporator temperature.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to a refrigeration system andmore particularly, to a dual-compressor refrigeration system havingeither a single evaporator or dual evaporators.

BACKGROUND OF THE DISCLOSURE

The present invention relates to household refrigerators operating witha vapor compression cycle and, more specifically, to refrigerators withtwo compressors.

SUMMARY OF THE DISCLOSURE

According to one aspect of the present disclosure, a refrigerationsystem includes a first and second compressor. The system also includesa condenser for receiving refrigerant gas from at least one of the firstcompressor and the second compressor. The condenser also condenses therefrigerant gas to a refrigerant liquid. The system also includes ahigh-stage first capillary for receiving the refrigerant liquid from thecondenser. A flash chamber for receiving a mixture of refrigerant gasand refrigerant liquid is also included in the system. The flash chamberseparates the refrigerant gas from the refrigerant liquid and providesthe refrigerant gas to the second compressor. The system includes alow-stage second capillary for receiving the refrigerant liquid from theflash chamber. The system also includes an evaporator for receiving therefrigerant liquid from the second capillary and evaporating the liquidto form the refrigerant gas that is supplied to the first compressor.

According to another aspect of the present disclosure, the firstcompressor supplies refrigerant gas to the second compressor, thecondenser receives refrigerant gas from the second compressor, and theflash chamber receives the mixture of refrigerant gas and refrigerantliquid from the high-stage capillary.

According to another aspect of the present disclosure, the flash chamberintercools the refrigerant gas supplied from the first compressor to thesecond compressor. The system may further comprise a second evaporatorfor receiving refrigerant liquid from the high-stage capillary. Thecondenser may receive refrigerant gas from both the first compressor andthe second compressor, and the flash chamber receives the mixture ofrefrigerant gas and refrigerant liquid from the second evaporator. Also,another aspect may comprise the first compressor comprising a high-stagecompressor and/or the second compressor comprising a low-stagecompressor.

According to yet another aspect of the present disclosure, the systemmay comprise a drier located between the condenser and the high-stagecapillary, wherein the drier receives the refrigerant liquid from thecondenser, and/or a first capillary located between the flash chamberand the high-stage capillary and a second capillary located between thelow-stage capillary and the evaporator.

According to another aspect of the present disclosure, the refrigerationsystem includes a high-state compressor and a low-stage compressor. Thesystem also includes a condenser for receiving refrigerant gas from atleast one of the high-stage compressor and the low-stage compressor andcondensing the refrigerant gas to a refrigerant liquid. The system alsoincludes a first heat exchanger for receiving the refrigerant liquidfrom the condenser and a flash chamber for receiving a mixture ofrefrigerant gas and refrigerant liquid from the first heat exchanger.The flash chamber separates the refrigerant gas from the refrigerantliquid and provides the refrigerant gas to the low-stage compressor. Thesystem also includes a second heat exchanger for receiving therefrigerant liquid from the flash chamber and an evaporator. Theevaporator receives the refrigerant liquid from the low-stage capillaryand evaporates the liquid to form the refrigerant gas that is suppliedto the high-stage compressor.

According to another aspect of the disclosure, the system may have thehigh-stage compressor supply refrigerant gas to the low-stagecompressor, the condenser receives refrigerant gas from the low-stagecompressor, and the flash chamber receives the mixture of refrigerantgas and refrigerant liquid from the first heat exchanger.

According to yet another aspect, the flash chamber intercools therefrigerant gas supplied from the low-stage compressor to the high-stagecompressor. The system may also comprise a second evaporator forreceiving refrigerant liquid from the first heat exchanger. Thecondenser receives refrigerant gas from both the high-stage compressorand the low-stage compressor and the flash chamber receives the mixtureof refrigerant gas and refrigerant liquid from the second evaporator.The system may also comprise a drier located between the condenser andthe first heat exchanger, wherein the drier receives the refrigerantliquid from the condenser.

According to yet another aspect of the present disclosure, therefrigeration system includes a first compressor and second compressor.The system also includes a condenser for receiving refrigerant gas fromat least one of the first compressor and the second compressor andcondensing the refrigerant gas to a refrigerant liquid. The systemincludes a high-stage first capillary for receiving the refrigerantliquid from the condenser and a first evaporator for receiving therefrigerant liquid from the high-stage capillary. The system alsoincludes a flash chamber for receiving a mixture of refrigerant gas andrefrigerant liquid from the first evaporator. The flash chamberseparates the refrigerant gas from the refrigerant liquid and providesthe refrigerant gas to the second compressor. The system also includes alow-stage second capillary for receiving the refrigerant liquid from theflash chamber. The system further includes a second evaporator forreceiving the refrigerant liquid from the low-stage capillary andevaporating the liquid to form the refrigerant gas that is supplied tothe first compressor.

According to another aspect of the present disclosure, the condenserreceives refrigerant gas from both the first compressor and the secondcompressor and condenses the refrigerant gas to a refrigerant liquid;the first compressor comprises a mid-stage compressor; and/or the secondcompressor comprises a low-stage compressor.

According to yet another aspect, the system may comprise: a drierlocated between the high-stage first capillary and the condenser,wherein the drier receives the refrigerant liquid from the condenser; athird capillary located between the high-stage capillary and the firstevaporator, wherein the third capillary receives the refrigerant liquidfrom the high-stage capillary; and/or a fourth capillary located betweenthe low-stage second capillary and the second evaporator, wherein thefourth capillary receives the refrigerant liquid from the low-stagesecond capillary.

These and other aspects, objects, and features of the present disclosurewill be understood and appreciated by those skilled in the art uponstudying the following specification, claims, and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a schematic view of a refrigeration system with a singleevaporator;

FIG. 2 is a pressure-enthalpy chart of the refrigeration system with thesingle evaporator;

FIG. 3 is a schematic view of a refrigeration system with dualevaporators; and

FIG. 4 is a pressure-enthalpy chart of the refrigeration system with thedual evaporators of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present illustrated embodiments reside primarily in combinations ofmethod steps and apparatus components related to using two compressorsin a refrigeration system that may be used in a refrigerator having justa refrigeration compartment or both a refrigeration compartment and afreezer compartment and that may be used in a standalone freezer havinga freezer compartment, which may all be more energy efficient and costeffective. Accordingly, the apparatus components and method steps havebeen represented, where appropriate, by conventional symbols in thedrawings, showing only those specific details that are pertinent tounderstanding the embodiments of the present disclosure so as not toobscure the disclosure with details that will be readily apparent tothose of ordinary skill in the art having the benefit of the descriptionherein. Further, like numerals in the description and drawings representlike elements.

For purposes of description herein, the terms “upper,” “lower,” “right,”“left,” “rear,” “front,” “vertical,” “horizontal,” and derivativesthereof shall relate to the disclosure as oriented in FIG. 1. However,it is to be understood that the disclosure may assume variousalternative orientations, except where expressly specified to thecontrary. It is also to be understood that the specific devices andprocesses illustrated in the attached drawings, and described in thefollowing specification, are simply exemplary embodiments of theinventive concepts defined in the appended claims. Hence, specificdimensions and other physical characteristics relating to theembodiments disclosed herein are not to be considered as limiting,unless the claims expressly state otherwise.

In this document, relational terms, such as “first” and “second,” “top”and “bottom,” and the like, are used solely to distinguish one entity oraction from another entity or action, without necessarily requiring orimplying any actual such relationship or order between such entities oractions. The terms “comprises,” “comprising,” or any other variationthereof are intended to cover a non-exclusive inclusion, such that aprocess, method, article, or apparatus that comprises a list of elementsdoes not include only those elements but may include other elements notexpressly listed or inherent to such process, method, article, orapparatus. An element preceded by “comprises . . . a” does not, withoutmore constraints, preclude the existence of additional identicalelements in the process, method, article or apparatus that comprises theelement.

Referring to FIGS. 1 and 3, a refrigeration system 10, 10 a can be usedfor both a single evaporator refrigerator 12 (FIG. 1) and a dualevaporator refrigerator 14 (FIG. 3) where a flash chamber 16 is usedwith first and second compressors 18 and 20, respectively. Therefrigeration system 10, 10 a further includes a condenser for receivinga refrigerant gas from at least one of the first compressor 18 and thesecond compressor 20 and condensing the refrigerant gas to a refrigerantliquid, and a high-stage first capillary 22 for receiving therefrigerant liquid from a condenser 30. The flash chamber 16 receives amixture of the refrigerant gas and the refrigerant liquid and separatesthe refrigerant gas from the refrigerant liquid and provides therefrigerant gas to the second compressor 20. The refrigeration system10, 10 a also includes a low-stage second capillary 24 for receiving therefrigerant liquid from the flash chamber 16, and an evaporator 34 forreceiving the refrigerant liquid from the second capillary 24 andevaporating the liquid to form the refrigerant gas that is supplied tothe first compressor 18. Additionally, the flash chamber 16 may also beused for intercooling the gas going from the first compressor 18 to thesecond compressor 20. For dual evaporator refrigerators 14, therefrigeration system 10 a is especially good where a first compartment26 (e.g., refrigerator compartment) requires a very low evaporatortemperature (for example, −25° C.) and a second compartment 28 (e.g.,freezer compartment) requires a controllable evaporator temperature (forexample, 5 to −15° C.). The schematic and pressure-enthalpy chart forthe proposed dual evaporator refrigeration system 10 a is shown below inFIG. 4. The schematic and pressure-enthalpy chart for the proposedsingle evaporator refrigeration system 10 is shown below in FIG. 2.

Referring now to FIG. 1, a refrigeration system 10 is shown having asingle evaporator subsystem 12. In the refrigeration system 10, ahigh-stage first compressor 18 supplies refrigerant gas to a low-stagesecond compressor 20, which then supplies the refrigerant gas to acondenser 30, which condenses the refrigerant gas to a refrigerantliquid. A high-stage first capillary 22 (also referred to herein as afirst heat exchanger) receives the refrigerant liquid from the condenser30 after passing through a drier 32. A flash chamber 16 receives amixture of the refrigerant gas and the refrigerant liquid from thehigh-stage first capillary 22 via an optional third capillary 38. Theflash chamber 16 separates the refrigerant gas from the refrigerantliquid and provides the refrigerant gas to the low-stage compressor 20to intercool the refrigerant gas supplied from the high-stage firstcompressor 18 to the low-stage second compressor 20. A low-stage secondcapillary 24 (also referred to herein as a second heat exchanger)receives the refrigerant liquid from the flash chamber 16. Then a singleevaporator 34 receives the refrigerant liquid from the low-stage secondcapillary 24 via an optional fourth capillary 40 to form the refrigerantgas that is supplied to the high-stage first compressor 18 via thelow-stage second capillary 24 and the high-stage first capillary 22,which function as heat exchangers.

Also illustrated in FIG. 1 are the various lines connecting thecomponents noted above. More specifically, line 42 connects an output ofthe high-stage first capillary 22 to an input of the high-stagecompressor 18; line 44 connects an output of the high-stage compressor18 to an intercooling mix point; line 46 connects the intercooling mixpoint to an input of the low-stage compressor 20; line 48 connects anoutput of the low-stage compressor 20 to an input of the condenser 30;line 50 connects an output of the condenser 30 to an input of the drier32; line 52 connects an output of the high-stage capillary 22 to aninput of the optional third capillary 38; line 54 connects an output ofthe optional third capillary 38 to an input of the flash chamber 16;line 56 connects a gas output of the flash chamber 16 to theintercooling mix point; line 58 connects a liquid output of the flashchamber 16 to an input of the low-stage second capillary 24; line 60connects an output of the low-stage second capillary 24 to an input ofthe optional fourth capillary 40; line 62 connects an output of theoptional fourth capillary 40 to the input of the single evaporator 34;and line 64 connects an output of the single evaporator 34 to an inputof the low-stage second capillary 24. These particular lines aredescribed for purposes of correlating the pressure-enthalpy chart inFIG. 3.

Referring now to FIGS. 2 and 4, FIG. 2 is an example of apressure-enthalpy chart of the refrigeration system 10 with a singleevaporator. FIG. 4 is an example of a pressure-enthalpy chart of therefrigeration system 10 a with dual evaporators (FIG. 3). In bothfigures, pressure is indicated on the y-axis and enthalpy is indicatedon the x-axis. Typically, enthalpy is in units of Btu/lb and pressure isin units of pounds per square inch (psi). The upside down U figure shownon the diagram designates the points at which the refrigerant changesphase. The left vertical curve indicates the saturated liquid curve andthe right vertical curve indicates the saturated vapor curve. The regionin between the two curves describes refrigerant states that contain amixture of both liquid and vapor. The locations to the left of thesaturated liquid curve indicate that the refrigerant is in liquid formand locations to the right of the saturated vapor curve indicate thatthe refrigerant is in vapor form. No additional pressure will change thevapor into a liquid at the critical point.

Referring now to FIGS. 1 and 2, the enthalpy and the pressure of therefrigerant gas may increase as the refrigerant gas exits the firstcompressor 18 (line 44). As refrigerant gas combines with refrigerantgas from the flash chamber 16 and the first compressor 18 (line 46), therefrigerant gas pressure remains constant but the enthalpy may decrease.As the refrigerant gas exits the second compressor 20, the pressure andthe enthalpy may increase (line 48). As the refrigerant passes throughthe condenser 30, the refrigerant is converted from a gas to a liquidwith the pressure remaining constant but the enthalpy may decrease (line50). As the refrigerant gas exits the high-stage first capillary 22, thepressure of the refrigerant gas may decrease but the enthalpy of therefrigerant gas may remain the same (line 52). As the refrigerantmixture exits an optional third capillary 38 (line 54), the pressure ofthe refrigerant mixture may decrease and enter the flash chamber 16. Theflash chamber may intercool the refrigerant mixture and separate therefrigerant liquid from the refrigerant gas. As the refrigerant gasexits the flash chamber 16 (line 56), the refrigerant gas may combinewith the refrigerant gas exiting the first compressor 18. As therefrigerant liquid exits the flash chamber 16 (line 58), the pressure ofthe refrigerant liquid may remain the same but the enthalpy maydecrease. As the refrigerant liquid exits the low-stage capillary 24,the pressure may decrease (line 60). As the refrigerant liquid exits anoptional fourth capillary 40, the pressure may continue to decrease(line 62). As the refrigerant liquid exits the evaporator 34 and changesinto a refrigerant gas (line 64), the refrigerant gas pressure mayremain constant while the enthalpy of the refrigerant gas may increase.

Referring now to FIG. 3, a refrigeration system 10 a is shown having adual evaporator subsystem 14, the condenser 30 receives refrigerant gasfrom both a low-stage compressor 18 and a mid-stage compressor 20 andcondenses the refrigerant gas into a refrigerant liquid. A high-stagefirst capillary 22 receives the refrigerant liquid from the condenser 30after passing through a drier 32. A first evaporator 36 receives therefrigerant liquid from the high-stage first capillary 22. A flashchamber 16 receives a mixture of refrigerant gas and refrigerant liquidfrom the first evaporator 36, wherein the flash chamber 16 separates therefrigerant gas from the refrigerant liquid and provides the refrigerantgas to the low-stage compressor 18. A low-stage capillary 24 receivesthe refrigerant liquid from the flash chamber 16. Then a secondevaporator 34 receives the refrigerant liquid from the low-stage secondcapillary 24 to form the refrigerant gas that is supplied to themid-stage compressor 20.

Also illustrated in FIG. 2 are the various lines connecting thecomponents noted above. More specifically, line 66 connects the outputof the low-stage second capillary 24 to an input of the mid-stagecompressor 20; line 68 connects an output of the mid-stage compressor 20to an input of the condenser 30; line 70 connects an output of thelow-stage compressor 18 to an input of the condenser 30; line 72connects an output of the condenser 30 to an input of the drier 32; line74 connects an output of the high-stage capillary 22 to an input of theoptional third capillary 38; line 76 connects an output of the optionalthird capillary 38 to an input of the first evaporator 36; line 78connects an output of the first evaporator 36 to an input of the flashchamber 16; line 80 connects a gas output of the flash chamber 16 to aninput of the high-stage first capillary 22; line 82 connects an outputof the high-stage first capillary 22 to an input of the low-stagecompressor 18; line 84 connects a liquid output of the flash chamber 16to an input of the low-stage second capillary 24; line 86 connects anoutput of the low-stage second capillary 24 to an input of the optionalfourth capillary 40; line 88 connects an output of the optional fourthcapillary 40 to the input of the second evaporator 34; and line 90connects an output of the second evaporator 34 to an input of thelow-stage second capillary 24. These particular lines are described forpurposes of correlating the pressure-enthalpy chart in FIG. 4.

Referring now to FIGS. 3 and 4, as the refrigerant gas enters thelow-stage and mid-stage compressors, the pressure and the enthalpy maydiffer (line 66), (line 82). However, because the compressor 18 is alow-stage compressor and the compressor 20 is a mid-stage compressor,the pressure at the outputs of the two compressors 18 and 20 is the same(lines 68 and 70) although the enthalpy is different. As the refrigerantpasses through the condenser 30, the refrigerant gas is converted to aliquid with a constant pressure and a decrease in enthalpy (line 72). Asthe refrigerant mixture exits the high-stage capillary 22 (line 74), thepressure of the refrigerant mixture may decrease while the enthalpyremains constant. As the refrigerant mixture exits the optional thirdcapillary 38, the pressure of the refrigerant mixture decreases furtheras the refrigerant mixture enters the first evaporator 36 (line 76). Asthe refrigerant mixture exits the first evaporator 36 and enters theflash chamber 16, the pressure of the refrigerant mixture remainsconstant but the enthalpy increases (78). The flash chamber 16 mayintercool the refrigerant mixture and separate the refrigerant gas fromthe refrigerant liquid. As the refrigerant gas exits the flash chamber16, the pressure of the refrigerant gas remains the same but theenthalpy increases (line 80) as the refrigerant gas re-enters thehigh-stage capillary 22. As the refrigerant gas exits the high-stagecapillary 22 for a second time the refrigerant gas may be directed toenter the first compressor 18 and increase the refrigerant gas enthalpybut maintain the refrigerant gas pressure (line 82).

As the refrigerant liquid exits the flash chamber 16, the enthalpy ofthe refrigerant liquid may decrease but may maintain pressure (line 84).As the refrigerant liquid exits the low-stage capillary, the enthalpymay continue to decrease (line 86). As the refrigerant liquid exits theoptional fourth capillary 40, the enthalpy of the refrigerant liquid mayremain the same but the pressure may further decrease (line 88). As therefrigerant liquid exits the second evaporator 34 and changes into arefrigerant gas (line 90), the refrigerant gas may be directed backthrough the low-stage capillary 34 and enter the first compressor 18 andmay maintain pressure but increase in enthalpy.

It will be understood by one having ordinary skill in the art thatconstruction of the described disclosure and other components is notlimited to any specific material. Other exemplary embodiments of thedisclosure disclosed herein may be formed from a wide variety ofmaterials, unless described otherwise herein.

For purposes of this disclosure, the term “coupled” (in all of itsforms, couple, coupling, coupled, etc.) generally means the joining oftwo components (electrical or mechanical) directly or indirectly to oneanother. Such joining may be stationary in nature or moveable in nature.Such joining may be achieved with the two components (electrical ormechanical) and any additional intermediate members being integrallyformed as a single unitary body with one another or with the twocomponents. Such joining may be permanent in nature or may be removableor releasable in nature unless otherwise stated.

It is also important to note that the construction and arrangement ofthe elements of the disclosure as shown in the exemplary embodiments isillustrative only. Although only a few embodiments of the presentinnovations have been described in detail in this disclosure, thoseskilled in the art who review this disclosure will readily appreciatethat many modifications are possible (e.g., variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters, mounting arrangements, use of materials colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter recited. For example,elements shown as integrally formed may be constructed of multiple partsor elements shown as multiple parts may be integrally formed, theoperation of the interfaces may be reversed or otherwise varied, thelength or width of the structures and/or members or connectors or otherelements of the system may be varied, and/or the nature or number ofadjustment positions provided between the elements may be varied. Itshould be noted that the elements and/or assemblies of the system may beconstructed from any of a wide variety of materials that providesufficient strength or durability, in any of a wide variety of colors,textures, and combinations. Accordingly, all such modifications areintended to be included within the scope of the present innovations.Other substitutions, modifications, changes, and omissions may be madein the design, operating conditions, and arrangement of the desired andother exemplary embodiments without departing from the spirit of thepresent innovations.

It will be understood that any described processes or steps withindescribed processes may be combined with other disclosed processes orsteps to form structures within the scope of the present disclosure. Theexemplary structures and processes disclosed herein are for illustrativepurposes and are not to be construed as limiting.

It is also to be understood that variations and modifications can bemade on the aforementioned structures and methods without departing fromthe concepts of the present disclosure, and further it is to beunderstood that such concepts are intended to be covered by thefollowing claims unless these claims by their language expressly stateotherwise.

What is claimed is:
 1. A refrigeration system comprising: a firstcompressor; a second compressor; a condenser for receiving a refrigerantgas from at least one of the first compressor and the second compressorand condensing the refrigerant gas to a refrigerant liquid; a high-stagefirst capillary for receiving the refrigerant liquid from the condenser;a flash chamber for receiving a mixture of the refrigerant gas and therefrigerant liquid, wherein the flash chamber separates the refrigerantgas from the refrigerant liquid and provides the refrigerant gas to thesecond compressor; a low-stage second capillary for receiving therefrigerant liquid from the flash chamber; and an evaporator forreceiving the refrigerant liquid from the second capillary andevaporating the liquid to form the refrigerant gas that is supplied tothe first compressor.
 2. The refrigeration system of claim 1, whereinthe first compressor supplies the refrigerant gas to the secondcompressor, the condenser receives the refrigerant gas from the secondcompressor, and the flash chamber receives the mixture of therefrigerant gas and the refrigerant liquid from the high-stagecapillary.
 3. The refrigeration system of claim 2, wherein the flashchamber intercools the refrigerant gas supplied from the firstcompressor to the second compressor.
 4. The refrigeration system ofclaim 1, further comprising a second evaporator for receiving therefrigerant liquid from the high-stage capillary, wherein the condenserreceives the refrigerant gas from both the first compressor and thesecond compressor, and the flash chamber receives the mixture of therefrigerant gas and the refrigerant liquid from the second evaporator.5. The refrigeration system of claim 1, wherein the first compressorcomprises a high-stage compressor.
 6. The refrigeration system of claim1, wherein the second compressor comprises a low-stage compressor. 7.The refrigeration system of claim 1, further comprising a drier locatedbetween the condenser and the high-stage capillary, wherein the drierreceives the refrigerant liquid from the condenser.
 8. The refrigerationsystem of claim 1, further comprising a first capillary located betweenthe flash chamber and the high-stage capillary and a second capillarylocated between the low-stage capillary and the evaporator.
 9. Arefrigeration system comprising: a high-stage compressor; a low-stagecompressor; a condenser for receiving a refrigerant gas from at leastone of the high-stage compressor and the low-stage compressor andcondensing the refrigerant gas to a refrigerant liquid; a first heatexchanger for receiving the refrigerant liquid from the condenser; aflash chamber for receiving a mixture of the refrigerant gas and therefrigerant liquid from the first heat exchanger, wherein the flashchamber separates the refrigerant gas from the refrigerant liquid andprovides the refrigerant gas to the low-stage compressor; a second heatexchanger for receiving the refrigerant liquid from the flash chamber;and an evaporator for receiving the refrigerant liquid from the secondheat exchanger and evaporating the refrigerant liquid to form therefrigerant gas that is supplied to the high-stage compressor.
 10. Therefrigeration system of claim 9, wherein the high-stage compressorsupplies the refrigerant gas to the low-stage compressor, the condenserreceives the refrigerant gas from the low-stage compressor, and theflash chamber receives the mixture of the refrigerant gas and therefrigerant liquid from the first heat exchanger.
 11. The refrigerationsystem of claim 10, wherein the flash chamber intercools the refrigerantgas supplied from the low-stage compressor to the high-stage compressor.12. The refrigeration system of claim 9, further comprising a secondevaporator for receiving the refrigerant liquid from the first heatexchanger, wherein the condenser receives the refrigerant gas from boththe high-stage compressor and the low-stage compressor and the flashchamber receives the mixture of the refrigerant gas and the refrigerantliquid from the second evaporator.
 13. The refrigeration system of claim9, further comprising a drier located between the condenser and thefirst heat exchanger, wherein the drier receives the refrigerant liquidfrom the condenser.
 14. A refrigeration system comprising: a firstcompressor; a second compressor; a condenser for receiving refrigerantgas from at least one of the first compressor and the second compressorand condensing the refrigerant gas to a refrigerant liquid; a high-stagefirst capillary for receiving the refrigerant liquid from the condenser;a first evaporator for receiving the refrigerant liquid from thehigh-stage capillary; a flash chamber for receiving a mixture of therefrigerant gas and the refrigerant liquid from the first evaporator,wherein the flash chamber separates the refrigerant gas from therefrigerant liquid and provides the refrigerant gas to the secondcompressor; a low-stage second capillary for receiving the refrigerantliquid from the flash chamber; and a second evaporator for receiving therefrigerant liquid from the low-stage capillary and evaporating therefrigerant liquid to form the refrigerant gas that is supplied to thefirst compressor.
 15. The refrigeration system of claim 14, wherein thecondenser receives the refrigerant gas from both the first compressorand the second compressor and condenses the refrigerant gas to therefrigerant liquid.
 16. The refrigeration system of claim 14, whereinthe first compressor comprises a mid-stage compressor.
 17. Therefrigeration system of claim 14, wherein the second compressorcomprises a low-stage compressor.
 18. The refrigeration system of claim14, further comprising a drier located between the high-stage firstcapillary and the condenser, wherein the drier receives the refrigerantliquid from the condenser.
 19. The refrigeration system of claim 14,further comprising a third capillary located between the high-stagefirst capillary and the first evaporator, wherein the third capillaryreceives the refrigerant liquid from the high-stage first capillary. 20.The refrigeration system of claim 14, further comprising a fourthcapillary located between the low-stage second capillary and the secondevaporator, wherein the fourth capillary receives the refrigerant liquidfrom the low-stage second capillary.